1. Field of the Invention
The present invention relates generally to a method and apparatus for packaging of semiconductor dice. More particularly, the present invention relates to a method and apparatus of packaging one or more semiconductor dice and providing redistributed input/output locations therefor without the use of a supporting substrate.
2. State of the Art
Interconnection and packaging-related issues are among the factors that determine not only the number of circuits that can be integrated on a chip, but also the performance of the chip. These issues have gained in importance as advances in chip design have led to reduced sizes of transistors and enlarged chip dimensions. The industry has come to realize that merely having a fast chip will not necessarily result in a fast system; the fast chip must also be supported by equally fast and reliable electrical connections. Essentially, the electrical connections, in conjunction with the packaging, enable the chip to receive and send signals and supply the chip power and a reference voltage (such as ground or other fixed bias voltage), and redistribute the tightly packed terminals (bond pads) of the chip to match the more widely spaced terminals of a carrier substrate and then to a circuit board.
One example of an integrated circuit device is known as a “flip-chip.” Flip-chip attachment generally includes electrically and mechanically attaching a semiconductor die by its active surface to an interposer substrate or other carrier substrate using a pattern of discrete conductive elements extending transversely therebetween. The discrete conductive elements are generally disposed on the active surface of the die during fabrication thereof, but may instead be disposed on the carrier substrate. The discrete conductive elements may comprise minute conductive bumps, balls, columns or pillars of various configurations. Each discrete conductive element is placed corresponding to mutually aligned locations of bond pads (or other, redistributed I/O locations) on the semiconductor die and terminals on the carrier substrate when the two components are superimposed. The semiconductor die is thus electrically and mechanically connected to the carrier substrate by, for example, reflowing conductive bumps of solder or curing conductive or conductor-filled epoxy bumps. A dielectric underfill may then be disposed between the die and the carrier substrate for environmental protection and to enhance the mechanical attachment of the die to the carrier substrate. For example, U.S. Pat. No. 5,710,071 to Beddingfield et al. discloses a fairly typical flip-chip attachment of a semiconductor die to a substrate and a method of underfilling a gap between the semiconductor die and substrate.
As new generations of integrated circuit products are released, the number of components used to fabricate them tends to decrease due to advances in technology even though the functionality of the products increases. Ongoing goals of the computer industry include higher performance, lower cost, increased miniaturization of components, and greater packaging density of integrated circuits in, for example, a flip-chip type assembly. However, flip-chip type assemblies including one or more bumped semiconductor dice and employing an interposer substrate between a bumped semiconductor die and a carrier substrate such as a circuit board may be undesirably thick due to the combined height of the die and interposer substrate. Such an interposer substrate may be utilized between the bumped semiconductor die or dice and circuit board to redistribute the large number of tightly packed terminals from the die to a standard interconnect outline on a circuit board. In an effort to limit the height of a flip-chip type assembly including a plurality of bumped semiconductor dice, the use of thin, flexible interposer substrates has been proposed. By way of example, U.S. Pat. No. 5,386,341 to Olson et al. discloses a thin, flexible substrate utilized as an interposer substrate between a plurality of bumped semiconductor dice and a circuit board. However, aligning each of the bumps on the semiconductor dice with the corresponding terminals on the interposer substrate is difficult and results in reliability issues. These reliability issues are only compounded with the increased miniaturization of components. Furthermore, interposer substrate technology has become highly sophisticated due to the increased miniaturization of components, which has increased the cost for such interposer substrates, in some instances, to approximately 30% of the total cost of the resulting assembly.
Therefore, it would be advantageous to provide a bumped semiconductor die assembly including one or more semiconductor dice which avoids the use of a conventional interposer substrate.